This application claims the priority of 197 37 704.1, filed Aug. 29, 1997, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a tube connection coupling of the type having a connection piece for receiving the end of a tube that can be inserted in the axial direction of the connection piece, and is provided with a toroidal member or flange which is to be supported on the connection piece in the inserting direction of the tube. A releasably inserted plug-in fork bears against the toroidal member, securing the end of the inserted tube against movement in a direction opposite the inserting direction of the tube. For this purpose, the connection piece has pairs of plug-through openings on opposing side walls thereof, through which respective prongs of the plug-in fork can be inserted.
A connection coupling of this type is disclosed in German Patent Document DE 35 17 488 C2 for connecting a tube to a radiator tank of a motor vehicle heat exchanger. There, the passage openings on the side walls of the connection pieces for receiving the plug-in fork consist of one pair respectively of oblong holes which are situated opposite one another in the insertion direction of the plug-in fork and which, measured in the tube inserting direction, are situated at the same height and extend in a straight line with a longitudinal oblong hole axis, transversely to the inserting direction of the tube and to the inserting direction of the plug-in fork. For mounting, the tube must first be pressed completely into the connection piece, preferably while inserting a sealing ring, and must then be held in this position until it is secured against outward movement, by inserting the plug-in fork.
In another tube connection coupling of this type, described in German Patent Document No. 196 21 283.9, the connection piece has at least one plug-in fork guide tab between a pair of plug-through openings for a respective plug-in fork prong, which plug-in fork guide tab bounds the plug-in fork inserting movement in the axial direction of the connection piece. The plug-in fork guide tabs prevent jamming of the plug-in fork in the axial direction of the connection piece during insertion, and ensure that, after being inserted through the plug-through openings in one connection piece side wall, the prongs reliably reach the opposite opening areas on the other connection piece side wall, without need of particular care in handling the plug-in fork.
One disadvantage of the above-described known couplings is that to achieve the sort of tube connection that is usually desired (that is, a connection which is under tension, is free from play and is therefore tight), the tube, to which a sealing ring is normally premounted on the tube torus, is completely inserted into the connection piece, and must be held in this position until the plug-in fork is inserted and secures the tube against outward movement. This makes the mounting and removal of the tube on the connection piece or pieces difficult, particularly where the tube connection cannot be inspected and/or is poorly accessible, and therefore requires virtually blind mounting or removal.
One object of the invention is to provide a tube connection coupling of the initially mentioned type which can be mounted and removed comparatively simply and reliably.
This and other objects and advantages are achieved by the tube connection coupling according to the invention, in which inserting bevels are assigned to at least a portion of the plug-through openings. These inserting bevels are shaped so that they cause a forcible displacement of the plug-in fork in the tube inserting direction as the plug-in fork is moved in the plug-in fork inserting direction. For mounting, therefore, the tube does not have to be inserted completely into the connection piece and held in there until the securing plug-in fork is inserted, as is necessary with prior art couplings. Rather, the tube need only be loosely inserted into the connection piece, sufficiently for the plug-in fork to be pushed in can reach around its toroidal member. Complete insertion of the plug-in fork then causes the remaining tube inserting movement, by means of which the toroidal member or flange of the tube is preferably pressed (without play) against a corresponding stop face on the connection piece, preferably by means of an inserted O-ring seal, on the one hand, and the plug-in fork on the other hand. This advantageous result is achieved by virtue of the fact that the inserting movement of the plug-in fork forcibly displaces it in the tube inserting direction by the effect of the inserting bevels, and therefore, by way of its contact on the torus, displaces the tube in the tube inserting direction.
It is understood that the shape and the arrangement of the inserting bevels are adapted to the shape of the plug-in fork in such a manner that, during the insertion, the plug-in fork is displaced in the tube inserting direction by the exact amount by which the tube, after its initial loose insertion into the connection piece, is still spaced away from its desired position in the completely mounted condition. If an O-ring seal is premounted on the tube, it is, for example, advantageous for the tube to be initially loosely inserted only to such an extent that the O-ring rests against the connection piece, without already having been pressed into it or having been pressed against it. This sealing pressing-in or pressing-on of the tube with respect to the connection piece by way of the O-ring is then carried out solely by the plug-in fork during its insertion by its forced displacement in the tube inserting direction caused by the inserting bevels.
Thus, with the coupling according to the invention, it is unnecessary to hold the connection tube during the insertion of the plug-in fork while exercising a pressure force acting in the tube inserting direction. The mounting can therefore be carried out easily and reliably, even when the position of the connection piece cannot be seen, or is poorly accessible. Removal is equally simple, in that only the plug-in fork need be unplugged, which can be accomplished by pressing the tube in the tube inserting direction as far as possible. The tube can then be removed from the connection piece.
In one embodiment of the tube connection according to the invention, two pairs of plug-through openings are provided for a two-prong plug-in fork. In this case inserting bevels are assigned at least to the plug-through openings which are in the front (in the plug-in fork inserting direction). These inserting bevels are specially shaped so that, by means of its forward area (the area of the free ends of the elastically spreadable plug-in fork prongs), the plug-in fork can be advanced unhindered from the inserting bevels into that area of the tube which is inserted into the connection piece. Thereafter, the inserting bevels will then interact with a rearward area of the plug-in fork, in which the spacing of its prongs (starting from a maximal distance, which corresponds approximately to the connection tube diameter and exists in a central plug-in fork area), is reduced in the direction of the rearward plug-in fork end. Because the plug-in fork moves with this rearward area against the inserting bevels, as desired, during the remaining inserting movement these inserting bevels cause a simultaneous displacement of the plug-in fork in the inserting direction of the tube.
In a further embodiment of the invention, the inserting bevels extend by means of a forward stopping surface, against which the plug-in fork moves, in the tube inserting direction in addition with at least one component included with respect to the plug-in inserting direction. That is, the pertaining surface normal vector is inclined relative to the plug-in fork inserting direction. This facilitates displacement of the plug-in fork in the tube inserting direction when it is inserted in the plug-in fork inserting direction. In the process, the inclined stop surface converts a portion of the plug-in fork inserting force (exerted in the inserting direction of the plug-in fork) into the required force pressing in the tube inserting direction.
In another embodiment of the tube connection coupling according to the invention, insertion aids are assigned to the forward plug-through openings. These are designed and arranged such that the plug-in fork is automatically inserted, by means of its free prong ends, into the area of the plug-through openings which is in the front in the tube inserting direction. This assures that the plug-in fork reliably reaches the desired position in which it extends behind the tube torus, without having to locate this position by probing with the plug-in fork. Simultaneously, the insertion aids may also operate as unplugging aids in that, during unplugging of the plug-in fork, they also press the plug-in fork in the tube unplugging direction, thereby freeing it of the contact pressure of the tube torus which facilitates the remaining pulling-out of the plug-in fork.
In yet another embodiment, the rearward plug-through openings are also provided with inserting bevels. For this purpose, the edges of these openings are correspondingly inclined in their area situated in the tube unplugging direction; that is, they extend in the plug-in fork direction, with a component which points in the tube inserting direction. During the plugging-in, as soon as it has reached the rearward plug-through openings with its free prong ends, the plug-in fork is pressed at the level of the forward and rearward plug-through openings, uniformly in the tube inserting direction. In this case, the inserting bevels of the forward and the rearward plug-through openings are designed and mutually coordinated so that, during insertion of the plug-in fork, they substantially simultaneously start to displace the plug-in fork in the inserting direction of the tube, and furthermore that upon further insertion, the plug-in fork is displaced in the tube inserting direction by all inserting bevels at essentially the same rate.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.